A significant variety of raised floor systems have been developed for use in commercial buildings. Such systems typically employ a plurality of height-adjustable pedestals supported on a main floor in a grid-like arrangement, and a plurality of removable floor tiles supported on the upper ends of the pedestals. The floor tiles are formed using numerous construction techniques, with one common technique employing a formed sheet metal pan defining an upwardly opening compartment which is filled with concrete. The space below the raised floor is utilized for accommodating cabling such as power, data and communication cabling, and in addition accommodates or defines ducts for heating, ventilating and air conditioning (HVAC).
In known floor systems employing composite steel and concrete floor tiles, which tiles in plan view are typically relatively large squares having side dimensions of about 24 inches, the tiles due to their construction and size are necessarily both bulky and heavy so that transport of such tiles over long distances is undesirably costly. Also, since the tiles are normally formed utilizing at least partially automated machinery capable of filling, leveling, curing and finishing the concrete, this normally mandates that the tiles be produced in rather large quantities at a centralized manufacturing location. Further, filling the metal pans with wet concrete and achieving a proper structural interconnection of the hardened concrete to the metal pan so as to provide the finished floor tile, when in use, with the necessary strength and durability, has presented an ongoing problem.
In a continuing development effort to improve the strength and durability of the floor tiles and specifically the structural connection of the concrete to the metal pan, the metal pan is typically provided with protrusions or barbs, particularly associated with the horizontal bottom wall of the pan, which protrude upwardly into the concrete poured into the pan in an effort to increase structural strength and structural interconnection of the concrete to the pan. While these techniques have proven to improve the strength characteristics, these techniques also increase the complexities associated both with the manufacture of the pan and the forming of the concrete therein.
In addition to the above, floor tiles of the type utilizing a wet concrete mix poured into a metal pan also typically utilize gypsum cement to create the wet concrete mix. This, however, creates additional disadvantages due not only to the expense of gypsum cement, but also due to its characteristics. Specifically, concrete mix formed using gypsum cement experiences dimensional instability in that the concrete dimensionally changes, specifically grows, during drying or curing. This hence creates significant dimensional instability with respect to the finished floor tile, and requires significant grinding or surface finishing of the exposed upper surface of the concrete in order to achieve the desired finished dimension of the floor tile. In addition, since wet concrete mix formed using gypsum cement requires utilization of a significant quantity of water, this reduces the strength properties of the concrete. Nevertheless, gypsum cement is typically utilized since curing of the concrete can be accomplished over a shorter number of days, typically three to four days, in contrast to the longer curing time of Portland cement, typically about seven days. Even so, this technique of forming floor tiles by depositing wet concrete mix into preformed metal pans is undesirable with respect to the time and space requirements demanded for production of such floor tiles, and hence this technique is limited to situations where these restrictions and the limitations imposed on the volume of production can be tolerated.
As an alternative to the manufacturing technique wherein wet concrete is poured into and cured within a metal pan, and the disadvantages associated with such technique, other floor tiles have been manufactured wherein a preformed block, frequently of wood, is positioned within a metal pan and secured therein, and is typically wholly enclosed within the pan by means of a separate covering or top walls. Such constructions, however, typically lack the strength and durability achieved utilizing floor tiles formed dominantly of concrete.
While attempts have been made to design and develop floor tiles employing a concrete block positioned within a metal pan by preforming the concrete and then forming the pan therearound, such as by shaping or bending the pan around a preformed block, such technique is also undesirable in terms of its processing limitations and the difficulty in achieving desired dimensional tolerances.
Examples of known constructions of raised floor arrangements, and specifically the floor tiles and pedestals associated therewith, are illustrated by U.S. Pat. Nos. 4,085,557, 4621,468, 4,719727, 4,914,881, 4,944,130, 5,057,355, 5,088,251, 5,333,423, 5,904,009, 6,418,697, 6,918,217 and 2003/097808 A1.
Accordingly, it is an object of this invention to provide an improved manufacturing process and manufacturing system for a floor tile for a raised floor system, which floor tile specifically involves a composite construction wherein a preformed concrete core or block is confined within a formed metal pan, with the construction of the floor tile providing structural fixation of the concrete block to the metal pan so as to provide significantly improved structural characteristics and integrity, while at the same time permitting the forming and utilization of a metal pan which is free of protrusions or the like which complicate the construction and configuration of the pan.
It is also an object of the present invention to provide an improved manufacturing process for the floor tile, as aforesaid, specifically with respect to the manner in which the concrete and metal pan are formed and secured together.
It is a further object of the invention to provide an improved manufacturing process for a floor tile, as aforesaid, wherein the tile, employing the preformed concrete block positioned in and adhered to a preformed metal pan, provides improvements with respect to strength of the resultant floor tile and at the same time permits the floor tile to be manufactured with less process time, while at the same time avoiding the undesired material variations, environmental variations and process control issues typically encountered when forming floor tiles using a wet concrete mix poured into the pan.
It is a still further object of the invention to provide an improved floor tile manufacturing process, as aforesaid, which avoids the manufacturing cycle limitations, namely time limitations, associated with conventional manufacturing processes which involve pouring wet concrete mix into preformed metal pans.
It is another object of the invention is to provide an improved floor tile for a raised floor, and the process of making the floor tile, wherein the concrete mix which is utilized for defining the block is effectively a dry mix, that is, a mix of concrete and aggregate which utilizes minimal water so as to permit forming and curing of the concrete block as a preform in a minimal period of time, with the preform thereafter being positioned in and adhesively adhered to the preformed metal pan.
A still further object of the invention is to provide a floor tile forming process, as aforesaid, which utilizes Portland cement for the dry concrete mix to achieve reduced material cost and material stability during drying or curing, with the overall curing time being significantly reduced by forming of the preformed concrete blocks from the dry concrete mix.
Still a further object of the invention is to provide a floor tile forming process, as aforesaid, which in a partially or fully automated manner permits floor tiles of uniform properties and consistencies to be efficiently manufactured at a very high rate, requiring minimal manual supervision and operation, and resulting in efficiencies of production and uniformity of end product.
Other objects and purposes of the invention will be apparent upon reading the following specification and inspecting the accompanying drawings.